1. Field of the Invention
The present invention relates to an apparatus for controlling an automatic clutch mounted on a vehicle such as an automobile.
2. Description of the Related Art
Automotive automatic transmissions employing torque converters are well known in the art. Since, however, automatic transmissions of this type are complex in mechanism and heavy and cause a large power loss due to the torque converter, there has recently been developed an electronically controlled automatic transmission which employs a conventional manual transmission and a conventional friction clutch and an electronic control unit for controlling their operation that has been manually performed by a human being.
When starting and changing speeds of an automobile incorporating such an electronically controlled automatic transmission, the clutch is first disengaged, gears are shifted, and then the clutch is engaged, in the same manner as a manual transmission is operated. The electronic control unit has a memory storing clutch operation data (representing the amount of engagement of the clutch and the speed of engagement of the clutch) for each gear position. When the automobile is started or the gears are changed, necessary data is read out of the memory, and the clutch is automatically controlled on the basis of the read-out data.
Where preset conditions (such as clutch conditions and engine conditions) are varied with time or due to temporary trouble, however, the clutch may be excessively slipped or engaged too quickly even if it is controlled on the basis of the stored data. When this happens, the clutch is worn soon or the driver feels uneasy about the clutch operation. These problems may be caused by a new automobile since the clutch characteristics slightly vary from automobile to automobile due to manufacturing errors of clutches and errors that may be produced when installing clutches on automobiles.
Some drivers connect a clutch relatively slowly for better riding comfort, whereas other drivers connect a clutch rather quickly to get the automobile started or shift gears rapidly. If the clutch is to be controlled on the basis of stored data, it is impossible to control the clutch in a way to meet individual driver's tastes.
One clutch control apparatus devised to solve the above problems is disclosed in Japanese Laid-Open Patent Publication No. 60-12343 filed by the present application. The disclosed clutch control apparatus has a plurality of memories storing basic clutch control data items, respectively. By operating a changeover switch, desired clutch control data which suits the driver's taste can be read out of one of the memories. However, since the available clutch control data items must be stored in the memories in an electronic control unit, the entire capacity of the memories is increased. The prior-art clutch control apparatus fails to solve the problems of time-dependent changes of the clutch and manufacturing and assembling errors of the clutch.